Chemical mechanical polishing retaining ring

Abstract

A chemical mechanical head includes a retaining ring to maintain a substrate beneath the mounting surface during polishing. The retaining ring has a lower portion with a bottom surface for contacting a polishing pad during polishing and made of a first material, such as plastic, and an upper portion made of a second, different material, such as metal.

What is claimed is:  
     
       1. A carrier head for a chemical mechanical polishing apparatus, comprising: 
       a substrate backing member;  
       a first chamber to provide a first downward pressure on the substrate backing member;  
       a retaining ring to maintain a substrate beneath the substrate backing member during polishing, the retaining ring vertically movable relative to the substrate backing member, the retaining ring including a lower portion having a bottom surface for contacting a polishing pad during polishing and made of a first material, and an upper portion made of a second, different material; and  
       a second chamber to provide a second independently controllable downward pressure on the retaining ring.  
     
     
       2. The carrier head of  claim 1 , wherein the lower portion is thicker than a substrate to be polished. 
     
     
       3. The carrier head of  claim 1 , wherein the upper and lower portions are substantially annular in shape. 
     
     
       4. The carrier head of  claim 1 , wherein the first material is a plastic. 
     
     
       5. The carrier head of  claim 1 , wherein the first material is Delrin. 
     
     
       6. The carrier head of  claim 1 , wherein the second material is a metal. 
     
     
       7. The carrier head of  claim 6 , wherein the second material is aluminum. 
     
     
       8. The carrier head of  claim 1 , wherein the lower portion is secured to the upper portion by screws. 
     
     
       9. The carrier head of  claim 8 , wherein the lower portion is secured to the upper portion by a key and key slot arrangement. 
     
     
       10. The carrier head of  claim 1 , wherein the upper portion is thicker than the lower portion. 
     
     
       11. The carrier head of  claim 1 , further comprising a housing, and wherein the substrate backing member is movable relative to the housing. 
     
     
       12. The carrier head of  claim 11 , wherein the retaining ring is movable relative to the housing. 
     
     
       13. A chemical mechanical polishing system, comprising: 
       a rotatable polishing pad;  
       a slurry supply to dispense a slurry onto the polishing pad; and  
       a carrier head having a substrate backing member, a first chamber to provide a first downward pressure on the substrate backing member, a retaining ring to maintain a substrate beneath the mounting surface during polishing, the retaining ring vertically movable relative to the substrate backing member, the retaining ring including a lower portion having a bottom surface for contacting a polishing pad during polishing and made of a first material, and an upper portion made of a second, different material, and a second chamber to provide a second independently controllable downward pressure on the retaining ring.